<div dir="auto"><div><br><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">пн, 19 февр. 2024 г., 20:59 Terje J. Hanssen via Cin <<a href="mailto:cin@lists.cinelerra-gg.org">cin@lists.cinelerra-gg.org</a>>:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><u></u>
<div>
Thirty years ago I tape recordered some hundreds of old genealogy
photos, which I now plan to convert from SD-DV files to burn on DVD
video discs.<br>
The camcordings were made with fade in/out, zoom closeups and pan
effects, which fit well at 2x playback speed and with additional
pause/play navigation on DVD videos.<br>
<br>
Signal/noise at 2x speed with same fps and bitrate (halph of the fps
are dropped), should result in output with 1/2 playback duration and
equivalent quality as normal speed.<br>
<br>
Yet I wonder if it possible in some way to achieve better quality if
also 2x bitrate and fps are possible to utilize temporarily as a
better quality base (downsampling), even if DVD video limits the fps
and bitrate?<br></div></blockquote></div></div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto">They are progressive (not interlaced) dv files, right? I only can think about fields-> frames conversion, that changes both frame size and fps. There might be some movement interpolation algorithms, or even neural nets nowadays, but I can't see any use of it directly in ffmpeg (for one command conversion) as long as output remain at 25 fps. But there might be some sideefects that makes viewing better/worse?</div><div dir="auto"><br></div><div dir="auto">Bitrate for consumer dv is fixed at 25Mbits, dv50 obviously goes above that *2, but not sure if you gain anything by transcoding into dv? (it was important when other hardware worked with those files, or they were transferred back to tape. But our current case is single Linux workstation only..?). mpeg2 dvd video yeah, seems to have gard upper cap on how big bitrate-wise it can go - you can try other stuff like custom matrixes and see if they improve quality ...</div><div dir="auto"><br></div><div dir="auto">I think there was yuvfps tool in mjpegtools, but I never used it ...</div><div dir="auto"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>
<br>
<br>
Here are my test samples so far:<br>
<br>
<font face="Courier New, Courier, monospace">du -sh dv95*<br>
</font>1) <font face="Courier New, Courier, monospace">2,0G
dv95.dv (input source)</font><br>
<br>
<font face="Courier New, Courier, monospace">2) 1,1G
dv95_2x_25fps.dv</font><br>
<font face="Courier New, Courier, monospace">3) 2,0G
dv95_2x_50fps.dv</font><br>
<br>
<font face="Courier New, Courier, monospace">4) 218M
dv95_2x_25fps.mpg</font><br>
<font face="Courier New, Courier, monospace">5) 218M
dv95_2x_50fps.mpg</font><br>
<font face="Courier New, Courier, monospace"><br>
<br>
1) <br>
ffprobe -hide_banner dv95.dv (source DV, Duration: 00:09:56.48)<br>
</font>
<blockquote><font face="Courier New, Courier, monospace">[dv @
0x55d65d6ca080] Estimating duration from bitrate, this may be
inaccurate</font><br>
<font face="Courier New, Courier, monospace">Input #0, dv, from
'dv95.dv':</font><br>
<font face="Courier New, Courier, monospace"> Metadata:</font><br>
<font face="Courier New, Courier, monospace"> timecode :
00:00:00:00</font><br>
<font face="Courier New, Courier, monospace"> Duration:
00:09:56.48, start: 0.000000, bitrate: 28800 kb/s</font><br>
<font face="Courier New, Courier, monospace"> Stream #0:0: Video:
dvvideo, yuv420p, 720x576 [SAR 16:15 DAR 4:3], 28800 kb/s, 60k
fps, 25 tbr, 60k tbn</font><br>
<font face="Courier New, Courier, monospace"> Stream #0:1: Audio:
pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s</font><br>
</blockquote>
<font face="Courier New, Courier, monospace"><br>
<br>
ffmpeg conversions using the FFmpeg setpts filter<br>
<a href="http://trac.ffmpeg.org/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video#setptsfilter" target="_blank" rel="noreferrer">http://trac.ffmpeg.org/wiki/How%20to%20speed%20up%20/%20slow%20down%20a%20video#setptsfilter</a><br>
</font><br>
<br>
2)<br>
<font face="Courier New, Courier, monospace">ffmpeg -i dv95.dv -vf
"setpts=0.5*PTS" -an dv95_2x_25fps.dv<br>
<br>
</font><font face="Courier New, Courier, monospace">ffprobe
-hide_banner dv95_2x_25fps.dv<br>
</font>
<blockquote><font face="Courier New, Courier, monospace">[dv @
0x5582eb685080] Estimating duration from bitrate, this may be
inaccurate<br>
Input #0, dv, from 'dv95_2x_25fps.dv':<br>
Metadata:<br>
timecode : 00:00:00:00<br>
Duration: 00:04:58.32, start: 0.000000, bitrate: 28800 kb/s<br>
Stream #0:0: Video: dvvideo, yuv420p, 720x576 [SAR 16:15 DAR
4:3], 28800 kb/s, 60k fps, 25 tbr, 60k tbn<br>
</font></blockquote>
<font face="Courier New, Courier, monospace"><br>
3) I wonder why the Duration is still </font><font face="Courier New, Courier, monospace">00:09:56.52 here ?<br>
<br>
</font><font face="Courier New, Courier, monospace">ffmpeg
-hide_banner -i dv95.dv -r 50 -vf "setpts=0.5*PTS" -an
dv95_2x_50fps.dv<br>
<br>
ffprobe -hide_banner dv95_2x_50fps.dv<br>
</font>
<blockquote><font face="Courier New, Courier, monospace">[dv @
0x55fe0b5bb080] Estimating duration from bitrate, this may be
inaccurate</font><br>
<font face="Courier New, Courier, monospace">Input #0, dv, from
'dv95_2x_50fps.dv':</font><br>
<font face="Courier New, Courier, monospace"> Metadata:</font><br>
<font face="Courier New, Courier, monospace"> timecode :
00:00:00:00</font><br>
<font face="Courier New, Courier, monospace"> Duration:
00:09:56.52, start: 0.000000, bitrate: 28800 kb/s</font><br>
<font face="Courier New, Courier, monospace"> Stream #0:0: Video:
dvvideo, yuv420p, 720x576 [SAR 16:15 DAR 4:3], 28800 kb/s, 60k
fps, 25 tbr, 60k tbn </font><br>
</blockquote>
<br>
4)<br>
<font face="Courier New, Courier, monospace">ffmpeg -hide_banner -i
dv95.dv -f dvd -target pal-dvd -aspect 4:3 -vf "setpts=0.5*PTS"
-an dv95_2x_25fps.mpg<br>
<br>
ffprobe -hide_banner dv95_2x_25fps.mpg<br>
</font>
<blockquote><font face="Courier New, Courier, monospace">[mpeg @
0x55a330208080] start time for stream 0 is not set in
estimate_timings_from_pts</font><br>
<font face="Courier New, Courier, monospace">Input #0, mpeg, from
'dv95_2x_25fps.mpg':</font><br>
<font face="Courier New, Courier, monospace"> Duration:
00:04:58.32, start: 0.540000, bitrate: 6115 kb/s</font><br>
<font face="Courier New, Courier, monospace"> Stream #0:0[0x1bf]:
Data: dvd_nav_packet</font><br>
<font face="Courier New, Courier, monospace"> Stream #0:1[0x1e0]:
Video: mpeg2video (Main), yuv420p(tv, progressive), 720x576 [SAR
16:15 DAR 4:3], 25 fps, 25 tbr, 90k tbn</font><br>
<font face="Courier New, Courier, monospace"> Side data:</font><br>
<font face="Courier New, Courier, monospace"> cpb: bitrate
max/min/avg: 9000000/0/0 buffer size: 1835008 vbv_delay: N/A</font><br>
<font face="Courier New, Courier, monospace">Unsupported codec
with id 98312 for input stream 0</font><br>
</blockquote>
<font face="Courier New, Courier, monospace"><br>
5)<br>
</font><font face="Courier New, Courier, monospace">ffmpeg
-hide_banner -i dv95.dv -f dvd -target pal-dvd -r 50 -vf
"setpts=0.5*PTS" -an dv95_2x_50fps.mpg</font><br>
<br>
<font face="Courier New, Courier, monospace">ffprobe -hide_banner
dv95_2x_50fps.mpg<br>
</font>
<blockquote><font face="Courier New, Courier, monospace">[mpeg @
0x555e13da2080] start time for stream 0 is not set in
estimate_timings_from_pts</font><br>
<font face="Courier New, Courier, monospace">Input #0, mpeg, from
'dv95_2x_50fps.mpg':</font><br>
<font face="Courier New, Courier, monospace"> Duration:
00:04:58.26, start: 0.520000, bitrate: 6118 kb/s</font><br>
<font face="Courier New, Courier, monospace"> Stream #0:0[0x1bf]:
Data: dvd_nav_packet</font><br>
<font face="Courier New, Courier, monospace"> Stream #0:1[0x1e0]:
Video: mpeg2video (Main), yuv420p(tv, progressive), 720x576 [SAR
16:15 DAR 4:3], 50 fps, 50 tbr, 90k tbn</font><br>
<font face="Courier New, Courier, monospace"> Side data:</font><br>
<font face="Courier New, Courier, monospace"> cpb: bitrate
max/min/avg: 9000000/0/0 buffer size: 1835008 vbv_delay: N/A</font><br>
<font face="Courier New, Courier, monospace">Unsupported codec
with id 98312 for input stream 0</font><br>
<font face="Courier New, Courier, monospace"> </font><br>
</blockquote>
<font face="Courier New, Courier, monospace"> <br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
</font><br>
</div>
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</blockquote></div></div></div>